Transactional Application Protocol for Inconsistent Replication, or TAPIR, is a new protocol for linearizable distributed transactions built atop a new replication protocol that provides no consistency guarantees. TAPIR eliminates expensive coordination from the replication layer, yet provides the same transaction model and consistency semantics as existing transactional storage systems (e.g., Google's Spanner). It can commit transactions in a single round-trip, greatly improving both latency and throughput relative to existing systems.

Distributed systems are traditionally designed independently from the underlying network, making worst-case assumptions about its behavior. Such an approach is well-suited for the Internet, where one cannot predict what paths messages might take or what might happen to them along the way. However, many distributed applications are today deployed in data centers, where the network is more reliable, predictable, and extensible. We argue that in these environments, it is possible to co-design distributed systems with their network layer, and doing so can offer substantial benefits.

Modern datacenter applications struggle with the need to access thousands of servers while still providing a fast response time to the user. In these situations, the user's overall request is not complete until the slowest of the subrequests has completed, meaning that network services must offer not just low latency but predictable latency. We are developing operating system and application-level techniques for building systems with predictable response time.

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Paul G. Allen School of Computer Science & Engineering
University of Washington